Abstract: High-frequency combustion infrared analyzer was applied to the determination of total carbon in samples of marine sediments. 50.0 mg of the sediment sample was placed onto 0.2 g of pure iron dust which was added to the combustion crucible prelimarily, and another portion of 0.2 g of pure iron dust was added and well-mixed with the sample. Then 1.6 g of tungsten grains were added to cover on the surface of the sample. Iron dust and tungsten grains were added as flux to promote fusion of sample. The crucible with sample and flux was placed into the analyzer and the determination was carried out through combustion and inspection as described in the working conditions of the instrument. Total carbon in 2 CRMs of GBW 07364 and GBW 07366 were determined by the prescribed procedure, giving results in consistency with the certified values, and RSDs (n=10) found for the 2 CRMs were 2.3% and 1.8% respectively. Detection limit (3s) found were 0.000 4%. 18 samples of marine sediments were analyzed for total carbon by the proposed method, giving results in consistency with the results found by the Vario EL element analyzer.